Bad clutch master cylinder and slave cylinder?

[Lug Nut]

02 RSV 15k miles. Bought the bike and shortly after flushed brakes and clutch and used Prestone DOT 4 synthetic brake fluid. Put rubber band on clutch lever over night and everything worked great. Noticed clutch MUCH harder to bleed than brakes. Also installed speedy bleeders at all locations. After rejetting carbs (Ivans jet kit, K&N air filters, Barons 4-2-4 Nasty Boys exhaust) and riding hard, noticed clutch slip in 3rd and 4th. Ordered SkyDocs full spring and clutch kit. Figured with increased power clutch slip was normal for this bike. While I was waiting for kit, I rode hard again and noticed slip again AND then the clutch lever got light/spongy. Put rubber band on it again and next day was fine. Rode 800 miles round trip and bike worked well but shifting wasn't easy and clutch got lighter as the trip went on. . Next couple rides the clutch lever was squeaky and light. Used PB Blaster on lever and was not squeaky. Last ride BARELY got bike home from having almost no clutch lever. Got SkyDocs kit installed (was anal about following directions, soaked discs for days in fresh oil, sanded steel plates with 320 grit to get cross hatch finish, used extra oil on everything on reassambly, etc). Buttoned it all up and went to start and had no clutch lever at all. So, skydoc_17 and others suggested slave cylinder was possibly bad. Noticed a few small drips of brake fluid under bike in general vanity of slave. So, ordered new OEM slave cylinder and installed. Bled fluid again and could not get air bubbles out of the line (unlike a month previous when I had great lever after difficult bleeding). Tried letting it sit with cap off master and rubber band on brake lever....tried squeezing 200 times slowly....could see small air bubble from smaller of two holes in bottom of master cylinder. Noticed the squeak in the lever was back and does NOT go away with lubricating this time. It is from the lever and not the black plunger thingy. So, fresh clutch and spring, fresh slave cylinder, fresh Mobil 1 synthetic and K&N filter, hours on trying to bleed system and no clutch. I ordered a rebuild kit for Master as well as an entire new OEM master as well. Will swap master and see if that works and if it does I will rebuild my original one to have as a spare. I tapped on banjo bolts to get air out etc....everything but reverse bleeding. Mechanic friend said to get a new master because air is being introduced into the system from someplace.

 

Any other ideas? If the new Master doesn't work and I can't bleed it correctly what would I look at next (no visible leaks)?

Edited April 25, 2016 by Lug Nut

[Yammer Dan]

Sounds like something is up with that master. Keep fingers crossed.

[bongobobny]

Well, it certainly isn't entirely unheard of for a master cylinder to go bad, it's just the USUAL suspect is the slave! Make sure you use new crush washers on the banjo bolt!

[yamagrl]

I prefer to bleed the clutch in a northerly direction.

 

Get a large syringe from a feed store. You can usually get at least 60 cc. You can get very large (100-200cc) on Ebay if you have the time to wait. You can also buy the same exact thing, except its very large syringe , made for force brake bleeding at Auto Zone. I don't recall the cost, maybe $20. Attach a clear hose to it.

 

Remove the banjo bolt on the clutch master cyl.

 

Place the end of the hose/banjo fitting into an empty plastic soft drink bottle. and kind of secure it so that it will kinda stay in place.

 

Fill the syringe with Brake fluid.

 

Attach it to the Slave bleed screw, open the screw and force fluid all of the way into the coke bottle. Tighten the screw. It may require a couple of syringe-fulls. Be mindful to not reintroduce air when refilling the syringe. If you get the syringe type from Auto Zone it will probably only require one fill.

 

You may have to remove the speed bleeders and reinstall the original bleed screw. Be sure to carefully teflon tape it so the bleed screw threads will be fairly sealed while you are forcing fluid in.

 

Now there should be no air in the line all the way up to the coke bottle.

 

Carefully, so as to not drip fluid on anything, reattach the the banjo fitting and gently finish forcing fluid into the master cyl reservoir... Be careful... it will SQUIRT OUT of that tiny hole.

 

This will only take 15-30 minutes

 

Viola!

 

Let me know if you have questions.

 

[Lug Nut]

If the new Master doesn't do it thn I will try the reverse bleeding! Anxious to try out this new clutch.....

[yamagrl]

http://uploads.tapatalk-cdn.com/20160425/e592203430340916a69594f35a9869de.jpg

[Zzyzx]

I had the same issue 2 years ago and thought it might be a master going bad.

Mine seemed to only have issues at higher elevations and when riding when it was really hot 100+degree days.

Found the fluid to be dirty so one day while at Condors place we did the reverse bleed on the entire system and that cured everything.

 

We did the reverse method on both mine and Condors bikes but without removing the banjo bolts.

We used an ear cleaning syringe (picture below) that you can pick up at most drug stores but you can use a syringe or bleeder like yamagrl pictured.

Also, it helps if you have someone to help while doing this since you will need to empty the master reservoir a few times during this process.

 

1 .Begin by turning the handle bars all the way to the right.

2. Place some plastic drop cloth over the lowers and any area where brake fluid could possibly run down. If brake fluid get on any paint is can ruin the paint.

3. Removing the clutch master reservoir cover. Be careful not to strip the screw heads.

4. Using a syringe suck out all of the old fluid from the reservoir.

5. Put a drain hose on the clutch bleeder and the other end into a glass jar then open up the bleeder and let it drain for a bit.

To help move things along you can use the syringe to push air into the larger hole of the master while the handle is pulled close. (Rubber band)

6. Once the master is clear of fluid make sure to wipe out the inside of any debris and remove any of the remaining old fluid.

7. Place the cover back onto the master to help prevent brake fluid squirting out during the back flushing.

8. Fill the syringe with new DOT-4 brake fluid and connect the end to the slave bleeder.

9. With the bleeder open about a 1/2 turn start SLOWLY pushing fluid backward from the slave bleeder to the master.

10. Once fluid starts heading upward occasionally check to see what is happening within the master and when the fluid has filled the master reservoir about half way full then draw the dirty/old fluid out and discard it.

11. Repeat this until the fluid runs clear then close off the slave bleeder and remove the syringe, etc.

12. Fill the master reservoir with new fluid from the fluid bottle, not the syringe, until the fluid is at the 3/4 mark on the glass view opening or, about 1/4" below the top of the reservoir.

13. Clean the inside of the master cover making sure to wipe clean the rubber gasket.

14. Reinstall the cover and try the clutch.

 

If this does not work for you then you may have a slave or master failure.

Hope this helps.

[Lug Nut]

Well took master cylinder apart....found small rubber piece floating free. It was a tiny nipple that was on a rubber stopper that fits at end of spring. I installed rebuild kit and it didn't seem right. Sure enough....the rebuild kit was different than the parts that were in the MC to begin with. I think I can reuse what I need to have. ****ing Amazon....of couse they listed this rebuild as the right one...not even close. Spring was much bigger and piston was taller/different design. Should have it done today after I look at and possibly get the 98 tour classic I'm looking at out of town.

[bongobobny]

Uh HUH!! Mystery solved!

[Lug Nut]

Got the new bike and bougjt a pneumatic brake bleeder...got clutch bled on Venture. New clutch setup is awsome (from skydoc_17). Working on 98 Arstc to make it a solo setup now...